[zygurat789]

My calabrese and purple sprouting are being attacked but not sprouts. Thet are inside chicken wire and under net. The leaves are being stripped between the veins and some have disappeared down to a 1 inch long stalk which is about 1/4 inch diameter.
I have put slug pellets in a jar - one small slug
I have put out sugar/flour/bicarb - untouched

Any ideas?

[BabbyAnn]

cabbage white caterpillars?  Calabrese and broccoli seem to be more readily attacked than sprouts and cabbages but eventually in a heavy infestation all brassicas are vulnerable.  Check for green or green/black caterpillars and remove them (how you dispose of them is up to you, but birds won't eat them and if they drop onto the ground, they are quite good at climbing back up onto the plants) 

Slugs and snails could still be a possibility if the pellets you put down are confined to a single jar - it may not be enough as a bait to attract them.

[zygurat789]

No sign of caterpillars and they are under netting to keep out the cabbage white.
Several jars around the plants

I'm still mystified 

[gobs]

Pigeons?

Yes, they do pick them through the netting. Depending on the support, they can land on that and so.

[viettaclark]

Slug pellets in a jar won't work!
You need to sprinkle very, very sparsely around the affected plants (I mean one or two every square foot!)
And don't forget to keep topping up......you'll find they disappear overnight.
Sounds like your greens have caterpillars! See if you can spot them then squish them!!

[BabbyAnn]

No sign of caterpillars and they are under netting to keep out the cabbage white.

there's netting and then there's netting    The first time I grew brassicas, I bought some netting labelled "bird and butterfly netting".   I can remember sitting on my patio and watching 2 cabbage white butterflies flutterbying around the cage and feeling secure in the knowledge that the plants would be safe.  I watched and ...  do my eyes deceive me but are they inside the cage now?   

The second time I grew brassicas, I used a finer pond netting - let's see them get through that!  The plants grew tall and started to get close to the netting but wasn't touching ... it didn't take very long to find the plants were stripped to skeletons.  I learned that some butterflies do not necessarily have to land on the leaf to lay eggs 

Like viettaclark, I'm almost certain it is caterpillars

[gobs]

No sign of caterpillars and they are under netting to keep out the cabbage white.

there's netting and then there's netting    The first time I grew brassicas, I bought some netting labelled "bird and butterfly netting".   I can remember sitting on my patio and watching 2 cabbage white butterflies flutterbying around the cage and feeling secure in the knowledge that the plants would be safe.  I watched and ...  do my eyes deceive me but are they inside the cage now?   

The second time I grew brassicas, I used a finer pond netting - let's see them get through that!  The plants grew tall and started to get close to the netting but wasn't touching ... it didn't take very long to find the plants were stripped to skeletons.  I learned that some butterflies do not necessarily have to land on the leaf to lay eggs 

Like viettaclark, I'm almost certain it is caterpillars

One just would notice those! But true. They do fly through the wider hole nettings. I just watched one today from close. They literally squeeze through like cat into a hole.

[zygurat789]

Yes it certainly looks like caterpillars and that's what the wife said BUT there isn't a single one to be seen anywhere and now they've started on the sprouts.
I've not had a look at night, is there a nocturnal caterpillar that hides in daylight?
Could it be some sort of miner or weevil?
I'd be happy with caterpillars, at least I could do something about them as suggested but there's nothing, not even leaves any more and another one has disappeared down to the stem.

[Comfortably Numb]

Have a little poke around in the soil around each plant.

 Some moth caterpillars feed on brassicas at night, and then hide in the soil during the day.

One large and ever growing caterpillar will strip a plant in very short order 

[Kajazy]

Anyone know how long it takes for the cabbage white eggs to hatch into caterpillars? I saw no less than THREE butterflies flitting around UNDER my butterfly netting today, but won't be able to get to the allotment to check for eggs/caterpillars till Tuesday at the earliest - will there be anything left of my brassicas??

[Gandan57]

Anyone know how long it takes for the cabbage white eggs to hatch into caterpillars? I saw no less than THREE butterflies flitting around UNDER my butterfly netting today, but won't be able to get to the allotment to check for eggs/caterpillars till Tuesday at the earliest - will there be anything left of my brassicas??

                                   

4-8 days from laying to hatching.